1. Technical Field
Embodiments described herein relate to integrated circuits, and more particularly, to techniques for testing a memory circuit.
2. Description of the Related Art
Memories typically include a number of data storage cells composed of interconnected transistors fabricated on a semiconductor substrate. Such data storage cells may be constructed according to a number of different circuit design styles. For example, the data storage cells may be implemented as a single transistor coupled to a capacitor to form a dynamic storage cell. Alternatively, cross-couple inverters may be employed to form a static storage cell or a floating gate metal-oxide semiconductor field-effect transistor (MOSFET) may be used to create a non-volatile storage cell.
During the semiconductor manufacturing process, variations in lithography, transistor dopant levels, etc., may result in different electrical characteristics between storage cells that are intended to have identical characteristics. Additional variation in electrical characteristics may occur due to aging effects within the transistors as the device is repeatedly operated. These differences in electrical characteristics between transistors can result in data storage cells that output different small signal voltages for the same stored data.
In order to detect data storage cells that have characteristics that may make operation problematic, various tests may be performed on the data storage cells. External test devices may be employed to provide test data for storage, different power supply voltage levels, different temperatures, and the like.